1. Field of the Invention
The invention relates to a method for the adjustment of the output signal that is produced by a device under test and that is dependent on a physical input variable, where the device under test has adjustment means that influence the output signal and that can be put into at least two adjustment states.
2. Description of the Background Art
A method of this type, where the device under test is a semiconductor chip that has a Hall sensor element integrated in a semiconductor substrate, is disclosed in DE 101 54 495 A1. For the adjustment of its output signal the device under test has adjustment means that can be put into at least two adjustment states. In a first step, the device under test, which is located in a wafer structure, is positioned at a first test device, at which a physical disturbance variable that affects the output signal of the device under test, namely a mechanical strain in the semiconductor substrate, has a predetermined disturbance variable value, and an input variable that is to be determined, namely a magnetic field, has a known input variable value. The adjustment means thereby have a first adjustment state. Now, the first measured value for the output signal of the device under test is determined. Then, the wafer is diced and the device under test is mounted in a package. The device under test located in the package is positioned at a further test device, where the disturbance variable has a further disturbance variable value and the input variable has the known input variable value. Now, for the first adjustment state, a further measured value is determined for the output signal and compared with the value determined at the first test device. In the event that the test state can be reproduced exactly at the further test device, all changes between the two output signals can be attributed to detrimental effects of the package in the form of mechanical stresses. In the event that the second value deviates from the first value too much, the adjustment state is changed in order to determine a further measured value for the output signal. The previously mentioned steps are repeated if necessary until the further measured value corresponds to the first measured value. The method has the disadvantage that the adjustment state changes can also affect the output signal of the device under test for the first disturbance variable value. Therefore, inaccuracies can arise during adjustment.
U.S. Pat. No. 6,154,872 A discloses a further method, in which devices under test are tested successively at various temperatures at various test devices. At every test device, a number of tests are performed. If a device under test does not pass the tests, it is marked with a color. Devices under test that pass the tests are installed in a package. This method has the disadvantage that a relatively high number of devices under test need to be culled out when only minimal tolerance for the devices under test can be allowed.
Therefore, there is the need to specify a method of the type initially mentioned that enables a quick and exact adjustment as well as a high product quality for the device under test.